1. Field of the Invention
This invention relates to and has among its objects the provision of novel potato products and novel processes for making them. It is a particular object of the invention to provide a precooked, non-par-fried potato piece, such as a French-fried potato, shoestring potato, and the like, which subsequently can be finish-cooked prior to consumption. It is another object of the invention to prepare a precooked boiling potato which can be finish-cooked by boiling in water.
Further objects of the invention will be evident from the following description wherein parts and percentages are by weight unless otherwise specified. Texture here relates to the surface layer of the strip and also includes the center. Good quality fried potato strips are rigid with a crisp surface layer and a firm but mealy inner core. Rigidity concerns the ability of the finished product to resist bending and is thus distinguished from texture. A thick, leathery surface can impart rigidity to a fry. It should be obvious that a crisp, rigid, rather than a leathery, rigid, finished fry is preferred. The terms "fat" and "oil" are used synonymously herein as designating an edible glyceride whether normally solid or liquid.
2. Description of the Prior Art
Most restaurants, including the large franchise chains prefer to prepare their French-fried potatoes from the frozen or chilled par-fried product rather than to go through the cumbersome procedure of preparing French fries from raw potatoes. Although these par-fried products offer convenience and savings in labor costs one problem which has beset the industry is that when the products are prepared for the table (either by oven heating or by deep-fat frying), they are unstable as to texture. Immediately after removal from the oven or deep-fat fryer, the potato strips have a desirable crisp texture, but as they cool they become limp and soggy. This problem is particularly acute in large restaurant operations. Guests who receive the first portions of each batch enjoy French fries of desirable crisp texture, whereas others who receive subsequent portions of the batches can only contemplate with dismay the soggy, limp strips on their plates.
Standard commercial French-fried potato products are par-fried prior to distribution. To prepare them for the table the product is given a finish-fry. The double frying increases the fat content of the French-fried product. Although some fat is necessary for the characteristic flavor of the French-fries, excessive fat is to be avoided for dietary and other reasons.
French-fried potatoes for home consumption are usually prepared by cutting raw potatoes into strips, blanching the potatoes in hot water, par-frying the potato strips in oil, and then preserving the strips by chilling or freezing them. To prepare them for consumption the French-fried potatoes are either baked in ovens or finish-fried in oil.
Potatoes, especially high solids tubers, tend to fall apart or slough when they are retorted in cans or pouches or when they are prepared for consumption by boiling. Thus, the types of potatoes that can be used for soups, stews, salads, whole-boiling potatoes, or the like, are limited to low-solids varieties.
In co-pending application Ser. No. 803,193, filed June 3, 1977, by Ng et al, now abandoned, a procedure for preparing precooked baking potatoes is described. Potatoes are cooked to their centers without damage to their surface tissue. An important feature of the cooking is that the temperature thereof for a part of the time, be above the temperature at which sloughing of the potato surface would occur if the potatoes were cooked to their centers at that temperature. Following the cooking procedure the potatoes are heated in air and then frozen or chilled to preserve them. It is noted in the application that the abovedescribed method cannot be used to prepare French-fried potatoes.
In another co-pending application Ser. No. 809,355, filed June 23, 1977, by Weaver et al, now abandoned, there is disclosed a process for making precooked fruits and vegetables. Potatoes, for example, are cooked to their centers at a temperature below the temperature at which sloughing of the surface tissue would occur if the potatoes were cooked to their centers at that temperature. Then, the so-treated potatoes are heated in air and then frozen or chilled to preserve them. It is noted also in this application that the method described therein cannot be used to prepare French-fried potatoes.
Finally, a process for preparing French-fried potatoes is described by Strong in Canadian Pat. No. 806,128, issued Feb. 11, 1969. In the patented process potato strips are blanched until all portions receive enough heat to turn them to a generally translucent condition throughout. The blanching may be conducted using steam for 2 to 10 minutes or hot water at 71.degree.-93.degree. C. for 3 to 8 minutes. The blanched strips are dehydrated in hot air at 65.degree.-177.degree. C. for 5 to 20 minutes to a moisture reduction of 20 to 30% of their initial weight. Then, the strips are par-fried at 149.degree.-191.degree. C. for 15 to 60 seconds and then frozen to preserve them.
The process of Strong has certain disadvantages, however. From an economic standpoint, the Strong process requires considerable expenditure of energy and money in the heating and par-frying steps. In addition, the texture of the final product is unpredictable in many instances the product is puffed and blistered. Furthermore, if the potatoes employed in the Strong process are high in reducing sugars, a lengthy preconditioning step is necessary to obtain an acceptable product.